A touch screen is an electronic visual display device that detects the presence and location of user touch inputs. Similarly, a touchpad is an input device including a surface that detects a touch-based inputs of users. So-called dual touch or multi-touch displays or track pads refer to devices that can identify the presence, location and movement of more than one touch input, such as two or three finger touches. More recently, multi touch user interfaces have become widely adopted with a diverse array of functions responding to touch gestures.
Gesture recognition in connection with single, dual or multi-touch devices refers to the interpretation of touch inputs, such as position and movement, into gestures. A recognized gesture may cause an in-focus application to perform one or more operations, such as scrolling, rotating, zooming, or selecting an object. Dual and multi-touch devices with the ability to recognize two or more touch positions allow for recognition of an increasing number of more complex gestures.